Method of carrying out metallurgical processes



METHOD OF CARRYING OUT METALLURGICAL PROCESSES Filed Dec. 21, 1960 RRINESCH Oct. 19, 1965 4 Sheets-Sheet l INVENTOR. RU DOLF RI NESCH HISATTORN EYS Oct. 19, 1965 R. RINESCH 3,212,880

METHOD OF CARRYING OUT METALLURGICAL PROCESSES Filed Dec. 21, 1960 4Sheets-Sheet 2 FIG. 2

INVENTOR. RUDOLF RINESCH BYd g 4;

HIS ATTORNEYS R. RINESCH 3,212,880

METHOD OF CARRYING OUT METALLURGICAL PROCESSES Oct. 19, 1965 4Sheets-Sheet 3 Filed Dec. 21, 1960 INVENTOR. RUDOLF RI NESCH I-HSATTORNEYS METHOD OF CARRYING OUT METALLURGICAL PROCESSES R. RINESCH Oct.19, 1965 4 Sheets-Sheet 4 Filed Dec. 21,

INVENTOR. RU DOLF RI NESCH HIS ATTORNEYS United States Patent 3,212,880METHOD OF CARRYING OUT METALLURGICAL PROCESSES Rudolf Rinesch, Linz,Austria, assignor to BOT Brassert Oxygen Techik A.G., Zurich,Switzerland, a company of Switzerland Filed Dec. 21, 1960, Ser. No.77,336 Claims priority, application Austria, Dec. 24, 1959, A 9,393/59;Mar. 21, 1960, A 2,171/60; Apr. 14, 1960, A 2,837/60 Claims. (CL 7552)The invention relates to a method of carrying out metallurgicalprocesses, e.g., for refining or pre-refining crude iron, for refiningsteel, for the preparation of alloys and the like.

Surface blowing processes utilizing oxygen gas, e.g., essentially pureoxygen, or oxygen-enriched gas, are already known in which crude iron isconverted into steel in a crucible, open hearth furnace, converter orother reaction vessel having a refractory lining. In a preferredembodiment of such processes, an oxygen jet is blown on the surface ofthe bath or charge through a blowing tube or lance disposed verticallyover the bath surface. It has also been proposed to introduce finelydivided or particulate basic materials, such as lime, under pressureinto the supply conduit for the blowing gas and to supply them to thebath together with the blowing gas. These known devices have variousdisadvantages. High requirements must be satisfied with regard to thepurity and the physical characteristics of the materials suppliedtogether with the blowing gas. If the materials contain combustibleimpurities, such as coal or iron particles, these impurities are ignitedin contact with the oxygen and often cause a destruction of the hoselines. For this reason nickelchronium steels have been used for thesupply conduits. As a result, the equipment becomes complicated andexpensive; it is no longer possible to move the blowing tube or lanceinto and out of the reaction vessel with the ease required for theperformance or refining processes. Besides, the equipment is subjectedto considerable mechanical wear. Aggregates having a particularlyuniform structure must be used to reduce this wear. Virtually only thosesubstances which have a uniform spherical particle structure aresuitable. These substances must be prepared in a special preliminaryprocess or particularly finely divided admixtures must be used. Lime inthis form, however, has the disadvantage of a great hydration.

It is an object of the invention to avoid these disadvantages. the fieldof application of processes and equipment using an oxygen-containingblast, e.g. oxygen or oxygen enriched gas, supplied from above and asupply of material in particulate solid, liquid or gaseous form. Asapplied to refining processes, the invention has as its object toprovide a greater latitude in the use of the starting materials to beprocessed, particularly regarding the chemical heat content of the crudeiron. It is a special object of the invention to enable the processingof crude irons having any desired carbon, phosphorus and siliconcontents without need for an addition of scrap or with the possibilityof adding any desired amounts of scrap. For this reason it is a specialobject of the method that it can be performed independently of a sourceof liquid crude iron.

The method, according to the invention, resides in that, at least duringpart of the blowing period, particulate solid, liquid and/ or gaseousmaterial which is to be added to the charge or bath, is added to, andpasses downwardly through, the interior of the blowing gas flowingthrough the tube or lance and the interior of the gas jet dischargingfrom the tube or lance. It is believed that such ma- Another object ofthe invention is to expand "ice terials impinge on the surface of thecharge or bath inside of the boundary of the reaction zone created byblowing of the gas jet on the surface of the charge or bath. Thematerial is introduced through use of a tube or downcomer extendingcentrally downwardly of the lance within the conduit or passage providedfor flow of the blowing gas. Where the material is in particulate solidform, e.g. finely divided lime, passage through the downcomer iseffected under no pressure, i.e. gravity flow. However, where liquid orgaseous material is to be added it is effected under pressure.

While it is to be understood the invention is not so limited, it isbelieved that use of the centrally disposed downcomer results inimpingement on the surface of the charge or bath of a jet having aconfiguration ranging from substantially a hollow truncated cone to ahollow cylinder, such jet providing an annular reaction zone with theadded material contacting the charge inside of such reaction zone.

The method according to the invention avoids the disadvantages of theknown equipment, in which finely divided material is introduced into thereaction vessel in suspension in the carrier gas. According to theinvention there is no danger of combustion of inflammable mate rials andthere is no mechanical wear from abrasion or other effects.

On the contrary, inflammable or combustible materials, such as coal,coke, oil, high calorific value gases, iron, silicon, maganese,aluminium or alloys of these substances can be introduced singly, incombination or in a mixture with slag-forming materials into theinterior of the reaction zone if the chemical heat content of the chargeto be blown is not sufficient for attaining or maintaining the desiredreaction temperature. For instance, if crude iron having a low carboncontent is to be converted into steel and scrap is to be melted at thesame time, the heat of combustion of the impurities contained in thecrude iron is not suflicient for attaining the refining temperaturenecessary for the conversion process, which temperature is 1600 to 1800C., and for maintaining this temperature during the process. In such acase, coal in small lumps or other heat-delivering substances can beadded according to the invention.

It has been proposed heretofore to add to the bath additional heatcarriers, such as ferrosilicon, ferromanganese, natural gas, coal gasand oil gas or to add oil or coallike substances together with therefining agent. The use of heat-supplying ferrous alloys, however, isvery expensive and the addition of oil and coal has not provedsatisfactory because the degree of utilization is relatively low. Alarge part of the oil or coal added is carried into the top part of thecrucible by the gas developed during the refining reaction. Thesesubstances are not burnt until they are being slopped out of thecrucible mouth. As a result, only the chimney is heated and thestructure in the upper part of the refining station is highly stressedwhereas the bath is not heated to the desired degree. The maximum degreeof utilization of the fuel supplied is 20 to 25%. Besides, specialrequirements regarding the purity of the material added must be met. Inthe case of coal it is possible to use only particularly pure grades,such as electrode carbon.

These difficulties may easily be avoided by means of the methodaccording to the invention. Optimal results are attained, if thecarbonaceous material in granular or powder form, or fuel gas, issupplied during the main boiling period, particularly between the 3rdand 15th minutes. In the known former method of working, introduction ofcoallike substances during the main boiling period was avoided becauseduring the main boiling period there was the strongest development ofgas and the fuel was utilized to the least degree as the fuel particleswere carried upwardly into the top part of the converter.

The previous difficulties are eliminated in the method of workingaccording to the invention. It is believed that this is accomplished dueto the formation of the above referred to annular reaction zone on thesurface of the molten charge which permits the carbonaceous materialssupplied to become fully effective without any danger that they could becarried away before contacting the bath. For this reason the degree ofutilization of the carbonaceous materials supplied in the methodaccording to the invention is as great as 90%. According to theinvention, carbonaceous or coallike materials of any desired kind may beused. It is not necessary to use particularly pure grades. Various kindsof coallike material, including inferior grades, have provedsatisfactory. Suitable materials include coke, lignite, any grades of(hard) coal, even lignite for low temperature carbonization and tarcoal.

The problem may also reside in melting a solid charge consisting ofcrude iron and scrap and in subsequently converting it into steel. Inthis case the necessary heat may also be supplied by an addition of coaland other combustible materials.

In a preferred embodiment of the invention, coal, iron ore andslag-forming substances are simultaneously introduced into the reactionvessel by means of a downcomer or the like into the interior of thereaction zone to form under a reducing atmosphere a liquid chargesimilar in composition to crude iron, and this charge is then convertedinto steel under an oxidizing atmosphere. The formation of a liquidcharge may be begun when the vessel is empty. It is also possible tocharge a portion of liquid crude iron at the beginning, and to increasethis charge by the addition of coal and ore. The supply rate should beso controlled that a liquid molten bath having the necessary temperatureis obtained. The conversion into steel is then carried out in the samevessel. Depending on the phosphorus content of the charge, the additionof slag-forming substances, such as CaO, during the blowing of therefining agent is continued until a reactive slag of high fluidity isformed, which takes up the major portion of the phosphorus.

After one or several deslagging operations the process may beterminated. In the last phase only oxygen is blown without an additionof admixtures.

The method according to the invention enables the very early formationof a reactive slag. The finely divided slag-forming substances suppliedin the interior of the jet are melted and react quickly with theimpurities in the iron. The method may be controlled in such a mannerthat the phosphorus content is reduced from 2.0% to 0.3-0.4% within afew minutes whereas the carbon content is still 2.0 to 2.5%. This hasnot been possible with any other process. A person skilled in the artwill understand that the latitude thus achieved in such a wide rangeenables a universal application of the method. Crude irons of anydesired composition, solid crude iron and even ores and scrap may beprocessed with or without an addition of liquid charging materials.

The method according to the invention may be combined with othermeasures which have proved satisfactory in special cases when refiningcrude iron. For instance, the liquid charge may be composed of a part ofthe finished steel and of the final slag of a preceding charge and maybe increased by an addition of ore and coal with simultaneous blowing.During a refining phase, e.g., when the carbon content is 2.5 to 2.0%and a high phosphorus content is still present, a sudden oversupply ofiron oxide, e.g., in the form of scarfing scale, may be added, followedby deslagging. This measure has the result of a very rapid removal ofphosphorus.

The method according to the invention may also be used for refining andafter-treating steel. The possibility of a mutual regulation of the kindand amount of the added materials relative to the blowing agent,particularly a suitable adjustment of the oxygen supplied in dependenceon the amount of coal or other carbonaceous material supplied, enablesthe selective adjustment of an oxidizing, neutral or reducing atmospherein the reaction vessel. For this reason it is possible, if desired, toprovide for a reducing after-treating phase after the production ofsteel, and alloying elements, such as Mn, Cr, Ni may be added to thefinished steel. In some cases it is necessary to heat the charge beforeadding alloying elements. This problem can also be easily solved withthe aid of the method according to the invention.

A particularly advantageous and economical method of alloying is enabledby the method according to the invention in that the alloying substancesare added in the form of oxides, such as chromium oxide, molybdenumoxide, manganese oxide and the like or in the form of ores containingsuch oxides, which ores are supplied in a mixture with reducingsubstances. Powdered coal or powdered aluminium are used as reducingsubstances and a reducing atmosphere is adjusted. Owing to the hightemperature in the reduction zone it is possible in this way to reducethe oxides and to alloy the iron. This has not been possible before withany other blowing process and it was necessary to use the much moreexpensive pure metals or master alloys With iron as alloying admixtures.

A particularly advantageous application of the invention involves thesimultaneous and continuous supply of oxygen and ores in hearth furnacesin the production of steel, using powdered or granular ores and, inaddition, slag-forming substances, such as lime, if desired, as solidmaterials. The ores may consist of powdered or granular iron ore or ofother ores. In addition to iron ores, the ores used may preferablyconsist of ores or ore concentrates of metals which are to remain asalloying elements in the steel. Suitable ores of this kind includeparticularly chromium ores, molybdenum ores and manganese ores.

With the aid of the method of working according to the invention theopen-hearth furnaces can be loaded to their full heat capacity. Theyield is increased and the output of existing plants is increased. Themost important advantage resides in that the refining process is greatlyaccelerated without disturbing secondary effects.

The invention includes also apparatus for carrying out the methoddescribed. An illustrative embodiment is shown on the drawing, in whichFIG. 1 is a diagrammatic representation of a plant, FIG. 2 an enlargedvertical sectional view of the mouth portion of the lance or blowingtube, and FIG. 3 a vertical sectional view of the upper part of theblowing device. FIG. 4 is a perspective view showing in section the jetproduced with the device. A further embodiment is shown in FIG. 5 whichis a diagrammatical longitudinal sectional view of a plant.

FIG. 1 shows a blowing tube 2 arranged to be lifted out of and loweredinto a reaction vessel 1, which in this case is a converter having arefractory lining. A support 3 having a rack 4 or another guide elementis provided to provide for a vertical guidance of the blowing tube. Theblowing tube (FIG. 2) consists of an inner tube 5, in which the blowingfluid, such as oxygen, is supplied under pressure, and an externalcooling shell 6. A guide tube 7 is arranged in the space between theinner tube 5 and the shell 6 to provide for a circulation of the coolingagent. In the mouth portion 8, which consists suitably of solidmaterial, the inner and outer tubes are integrally connected and formthe nozzle 9, which in the illustrative embodiment has the form of aLaval nozzle g iying rise to an expansion zone. Somewhat above its mouththe inner tube 5 is constricted to form a throttle 10. A downcomer 11 iscentrally disposed in the blowing tube. The lower end of the downcomeris adjacent to the throttle. The upper portion of the downcomer extendsthrough the wall 13 of the oxygen supply conduit 5, which is curved atthe top. By means of a stuffing box 14 and a gasket 16 which can betightened by screws 15 the upper part 12 of the downcomer is sealedagainst the insertion opening 17, which carries a flange 18 (FIG. 3).Above the stuffing box a flange 19 is welded to the downcomer and isconnected to the flange 18 by screws 20. By an adjustment of the screws20 the downcomer can be axially displaced relative to the blowing tubein the direction thereof. At the upper end the downcomer is connected toa hopper 21, which, in this case, widens like a funnel and serves forcharging solid materials. The hopper 21 communicates with the outeratmosphere. 22 is a valve consisting, e.g., of a slide valve. As hasbeen mentioned above and indicated with dash lines in FIGURES 1 and 2,the downcomer with the hopper 21 is axially displaceable relative to theinner tube 5. It is believed that when the downcomer is in its lowermostposition the expansion cone has the smallest size and the annularreaction field on the surface of the charge has the smallest diameter.Lifting the downcomer causes an increase of the generating angle of thecone and of the diameter of the reaction field. This enables a verysimple and practical additional adjustment for the control ofmetallurgical processes.

FIG. 4 shows what is believed to be the lower part of hollow-conicaljets thus produced. 23 is a jet of relatively small diameter, whichresults in the formation of the reaction ring 24. 25 is a jet larger indiameter to form the reaction ring 26 correspondingly larger indiameter. The materials are introduced into the interior 27 of thereaction ring.

As is apparent from FIG. 1, the funnel-shaped hopper 21 at the upper endof the downcomer is disposed adjacent to a charging device whichconsists of a supply vessel 28 and a belt conveyor 29. The belt conveyormay be provided with a weighing device and may be pivotally mounted toenable the feeding operation to follow the vertical lifting and loweringmovement of the downcomer and blowing tube. Instead of the beltconveyor, a feed tube with conveyor screw may be used; this feed tube ispreferably filled with inert gas.

The dimensions of the blowing device and, in accord ance therewith, thesize of the reaction zone may be adjusted to the size of the charge tobe blown. For a charge of 5 to 6 metric tons it is desirable to use ablowing tube having an inner tube 30 mm. in diameter at the throttle 10.The axially inserted downcomer has in this case an outside diameter ofabout 25 mm. and an inside diameter of about 20 mm.

Correspondingly larger dimensions are used for larger charges.

FIG. 5 shows an open hearth furnace wherein 30 is the roof, 31 the bathand 32 are the doghouses of the furnaces. The blowing device 33 consistsof a blowing tube 34 surrounded by a cooling shell and a downcomer 35centrally disposed in the blowing tube extends vertically through theroof 30. The central downcomer serves for feeding solid materials and,as has been described more in detail hereinbefore, can be lifted andlowered relative to the blowing tube. The upper end 36 of the downcomer,where the latter communicates with the outside atmosphere, is suitablyflared like a funnel. 37, 33 and 39, respectively, designate the oxygensupply conduit and the conduits for the supply and discharge of thecoolant. Where the blowing device 33 passes through the furnace roof 30it is surrounded by a cooling cylinder 40 having a water inlet andoutlet 41 and 42, respectively, and is guided in this cooling cylinderso that the device can be vertically lifted and lowered. Conveyor belts43 and 44 are disposed above the blowing device and are fed with ore andslag-forming materials from supply containers 45 and 46. Owing to thedescribed vertical adjustability of the blowing device over the bathsurface and the controllable shape of the jet, a reaction field 47 isbelieved produced on the bath surface; the ore and, if desired, othermaterials are introduced under no pressure into the interior of thisfield. Thus the process can be controlled as desired without overheatingand other disturbing secondary elfects.

The following examples illustrate the present invention without,however, limiting the same thereto.

Example 1.Conversion of steel-making crude iron into steel 50 kg. ofscarfing scale and 30 kg. bauxite were added to a crucible charge of 400kg. scrap and 6,540 kg. liquid crude iron having a composition of 4.12%C, 0.85% Si, 1.65% Mn, 0.196% P, 0.060% S. Then a blowing device asexplained more fully in FIGS. 1 to 3 of the drawings was moved into thecrucible. The inner tube had a diameter of 30 mm. at the throttle andthe downcomer had an inside diameter of 20mm. and extended about 15 mm.below the throttle into the conically widening mouth portion of thenozzle. The nozzle orifice was adjusted to a distance of 400 mm. fromthe bath surface and oxygen blowing started with a pressure of 14kg./sq. cm. superatmospheric pressure. A reaction zone was formed on thebath surface. 450 kg. lime dust were introduced under no pressure duringa blowing period of 15.5 minutes into the interior of the jet by meansof the downcomer. By the expanding gas the lime dust was sucked from themouth of the downcomer and fell into the interior of the reaction zone.Towards the end of the blowing period, kg. broken limestone were addedin portions by means of a chute while the downcomer was closed.

Then the oxygen supply was interrupted, the blowing device moved out ofthe crucible, the crucible was tilted and a steel sample taken, whichhad the following composition: 0.02% C, 0% Si, 0.20% Mn, 0.011% P,0.014% S.

The bath was deslagged. The temperature was 1605 C. The steel wastapped. The recovery was 89%.

Example 2.C0nversion of crude iron having a particularly low carboncontent and a high phosphorus content into steel 150 kg. scale and 50kg. bauxite were added to a charge of 6,540 kg. liquid crude iron havinga composition of 1.98% C, 0.72% Si, 0.15% Mn, 1.390% P, 0.052% S andhaving a temperature of 1350 C. A blowing device as has been describedin detail in the drawings and in the foregoing example was moved intothe crucible. The distance of the nozzle orifice from the bath surfacewas 600 mm. Oxygen blowing began at a pressure of 10 kg./sq. cm.superatmospheric pressure. A reaction zone was formed. During a blowingperiod of 13 minutes, 450 kg. lime dust were introduced under nopressure into the interior of the jet by means of the downcomer and weresucked from the mouth of the downcomer and fell into the interior of thereaction zone. After this first blowing period the oxygen supply wasinterrupted, the blowing device moved out of the crucible, the crucibletilted and samples of steel and slag taken. The steel had the followingcomposition: 1.14% C, 0.02% Si, 0.07% Mn, 0.187% P, 0.043% S. The slaghad the following composition: 15.23% FeO, 0.74% MnO, 9.84% SiO 39.40%0.210, 4.46% MgO, 18.21% P 0 8.25% A1 0 The temperature was 1520 C.

The bath was deslagged, the crucible brought into blowing position andadditional slag-forming substances, consisting of kg. scarfing scale, 50kg. bauxite and 400 kg. lime in lumps added through a chute. Then theblowing tube was inserted into the crucible and the blowing continuedfor 6.5 minutes under an oxygen pressure of 14 kg./ sq. cm. and withnozzle orifice at a distance of 400 mm. from the bath. During this lastblowing period the downcomer was maintained closed by a valve. After theblowing was terminated a steel sample was taken and had the followingvalues: 0.02% C, 0% Si, 0.03% Mn, 0.015% P, 0.021% S. The temperaturewas 1610 C.

After deslagging and thickening of the slag the steel was tapped andteerned. The recovery was 85.3%.

A charge of 4,910 kg. crude iron having a composition of 4.10% C, 0.75%Si, 1.60%.Mn, 0.170% P and 0.050% S was blown and converted into steel.The tapping temperature was to be 1640 to 1650 C. In view of thecomposition of this crude iron, 12% scrap, equal to 590 kg. scrap, couldbe melted together with the crude iron. It was desired, however, toprocess 1700 kg. scrap, which is 25.7%. The problem to be solved residedin the additional melting of 1110 kg. scrap. The charge was to be heatedby an addition of coke breeze. The coke breeze available had thefollowing analysis: 17.10% H O, 10.99% ash, 0.91% S (dry), 72.12% C(dry) and 1.76% volatile constituents. Its gross calorific value was5868 kg.-cal., the net calorific value was 5754 kg.-cal. Its grain sizewas to 3 mm.

A charge consisting of 4,910 kg. crude iron and 1,700 kg. scrap wasintroduced into the crucible provided with a refractory lining. 500 kg.lump lime, 50 kg. scarfing scale, 30 kg. bauxite and 20 kg. fluorsparwere added as slag-forming admixtures. A blowing device of the typedescribed herein was set to a distance of 600 mm. from the bath surface;oxygen was supplied under a pressure of to 11 kg./sq. cm.superatmospheric pressure. From the 3rd to the 12th blow minute, 212 kg.coke breeze of the composition described hereinbefore were introducedunder no pressure into the interior of the jet by means of thedowncomer. Deslagging was eifected after a total blow time of 21minutes. The final analysis of the resulting steel was: 0.05% C, 0.18%Mn, 0.011% P. The temperature was 1650 C.

The efiiciency of the fuel added according to the invention iscalculated as follows: In view of the values.

C steel=0.15 kg.-cal./kg. C. 1 kg. C CO=2440 kg.-cal. s (heat of fusionof steel) =60 kg.-cal./ kg.

the following heat quantities are required for heating 1110 kg. scrapfrom 20 C. to 1650 C. and for supplying the heat of fusion:

192 m X 100 9 l Example 4.Heating of a charge during the main boilingperiod by means of powdered coal =139 kg. 0:192 kg. coke breeze Using acharge of 5,330 kg. crude iron having a similar composition as inExample 3, 1,400 kg. scrap (20.8%) were melted. Powdered coal having agrain size of 0 to 3 mm. and the following composition: 8.00% water,6.28% ash, 0.76% S (dry), 76.65% C (dry), 4.07% H 4.39% O +N was usedfor heating the charge. Its gross calorific value was 7440 kg.cal., thenet calorific value was 7128 kg.-cal.

The method of working was the same as in Examp1e 3. The blowing beganafter the charge had been introduced and 500 kg. lump lime, 50 kg.scarfing scale and 30 kg. fluorspar added. The distance of the blowingtube from the bath surface was 700 mm. By means of the downcomer, 240kg. powdered coal were added from the 3rd to the 13th blow minutes.Deslagging was effected at the end of the refining process. The steelhad a composition of 0.06% C, 0.38% Mn, 0.010% P. The temperature was1705 C. The degree of utilization of the powdered coal'was 72%.

Example 5 .Heating of a charge during the main boiling period by meansof lignite breeze Using a charge of 5320 kg. crude iron having a similarcomposition as in Example 3, 1400 kg. scrap (20.2%) were melted. To heatthe charge, lignite breeze having the following composition: 17.41%water, 22.72% ash, 1.63% S (dry), 56.86% C (dry) and 8.33% volatiles wasused. The gross calorific value was 5048 kg.-cal., the net calorificvalue was 4863 kg.-cal.

The method of working was the same as in Examples 3 and 4. The blowingbegan after the charge had been introduced and 550 kg. lump lime, 50 kg.scarfing scale, 30 kg. bauxite and 30 kg. fluorspar added. The distanceof the blowing tube from the bath surface was 700 mm. By means of thedowncorner, 350 kg. lignite breeze were added from the 3rd to the 14thminute of the blow. Deslagging was effected at the end of the refiningprocess. The steel had a composition of 0.07% C, 0.37% Mn, 0.009% P. Thetemperature was 1645 C. The degree of utilization of the lignite breezewas 60% Example 6.Heating of a melt under reducing conditions A chargewas formed from 300 kg. scrap and 6400 kg. liquid crude iron, having acomposition of 4.08% C, 0.89% Si, 1.47% Mn, 0.142% P, 0.057% S. Afteraddition of 50 kg. scale, 30 kg. bauxite and 450 kg. lime in lumps thecharge was blown with oxygen using a blowing device of the typedisclosed herein but with a closed downcomer (pressure 14 kg./sq. cm.superatmospheric pressure, nozzle distance 400 mm) After a blowingperiod of 16.5 minutes, during which kg. broken limestone were added inportions through a chute, the supply of oxygen was interrupted, theblowing tube withdrawn and samples taken. The composition of the steelwas: 0.03% C, 0% Si, 0.27% Mn, 0.022% P, 0.030% S. The temperature was1610 C.

This temperature was increased. After the bath had been completelydeslagged the crucible was again moved to its blowing position and theblowing device inserted into the crucible. The distance from the bath ofthe blow ing device was adjusted to 400 mm., the oxygen pressure wasadjusted to 6 kg./sq. cm. superatmospheric pressure and the blowing ofthe bath continued for 5 minutes. At the same time, 80 kg. powdered cokeand 12 kg. lime dust were introduced through the downcomer under nopressure into the interior of the reaction zone. After this heatingperiod the oxygen supply was interrupted and another sample was taken.The composition of the steel was as follows: 0.09% C, 0% Si, 0.27% Mn,0.025% P, 0.025% S. The temperature was 1640 C. The steel was tapped andteemed. The recovery was 88.5%.

Example 7.Heating of a melt under neutral conditions A charge was formedfrom 350 kg. scrap and 6330 kg. liquid crude iron, having a compositionof 4.01% C, 0.90% Si, 1.40% Mn, 0.17% P, 0.050% S and 50 kg. scale, 30kg. bauxite and 450 kg. lime in lumps were added. Then the charge wasblown with oxygen using a blowing device of the kind disclosed hereinbut with the downcomer closed (pressure 14 kg./sq. cm., nozzle distance400 mm.). After a blowing period of 16 minutes, during which kg. brokenlimestone were supplied in portions through a chute, the oxygen supplywas interrupted, the blowing tube removed and samples taken. Thecomposition of the steel was: 0.05% C, 0% Si, 0.27% Mn, 0.018% P, 0.025%S. The temperature was 1580 C.

This temperature was increased. After the bath had been completelydeslagged the crucible was moved to its blowing position and the blowingdevice introduced into the crucible and adjusted to a distance of 400mm. from the bath. The oxygen pressure was adjusted to 7 kg./ sq. cm.superatmospheric pressure and the blowing of the bath continued for 6minute. At the same time, 80 kg. powdered coke and 12 kg. lime dust wereintroduced under no pressure through the downcomer into the interior ofthe reaction zone. After this heating period the oxygen supply was shutoff and another sample taken. The composition of the steel was asfollows: 0.05% C, Si, 0.25 Mn, 0.018% P, 0.023% S. The temperature was1630 C. The steel was tapped and teemed. The recovery was 88.9%.

Example 8.Heating of a melt under oxidizing conditions A charge wasformed from 400 kg. scrap and 6450 kg. liquid crude iron having acomposition of 4.10% C, 0.95% Si, 1.50% Mn, 0.164% P, 0.055% S and 50kg.scale, 30 kg. bauxite and 450 kg. lime in lumps were added. Then thecharge was blown with a blowing device as in the previous examples butwith downcomer closed (pressure 14 kg./ sq. cm. superatmosphericpressure, nozzle distance 400 mrn.). After a blowing period of 16minutes, in which 90 kg. broken limestone were added in portions througha chute, the oxygen supply was interrupted, the blowing tube removed andsamples taken. The composition of the steel was: 0.04% C, 0% Si, 0.30%Mn, 0.027% P, 0.023% S. The temperature was 1590 C.

This temperature was increased. After the bath had been completelydeslagged the crucible was moved to its blowing position and the blowingdevice inserted into the crucible and adjusted to a distance of 400 mm.from the bath. The oxygen pressure was adjusted to 7 kg./sq. cm.superatmospheric pressure and the blowing of the bath continued for 7minutes. At the same time, 80 kg. powdered coke and 12 kg. lime dustwere added under no pressure through the downcomer into the interior ofthe reaction zone. After the heating period the oxygen supply was shutoff and another sample taken. The composition of the steel was: 0.02% C,0% Si, 0.23% Mn, 0.018% P, 0.025% S. The temperature was then 1665 C.The steel was tapped and teemed. The recovery was 88.0%.

Example 9.Alloying a melt with simultaneous neutral heating A charge wasformed from 300 kg. scrap and 6230 kg. liquid crude iron having acomposition of 4.12% C, 0.97% Si, 1.42% Mn, 0.170% P and 0.044% S. Afteran addition of 50 kg. scale, 30 kg. bauxite and 450 kg. lime in lumpsthe charge was blown with the blowing device as in the previous examplesbut with the downcomer closed (pressure 14 kg./sq. cm. superatmosphericpressure, nozble distance 400 mrn.). After a blowing period of 15.5minutes, between the sixth and twelfth minutes of which 80 kg. brokenlimestone were added in portions, the oxygen supply was interrupted, theblowing tube withdrawn and a sample taken. The composition of the steelwas as follows: 0.03% C, 0% Si, 0.30% Mn, 0.018% P, 0.027% S. Thetemperature was 1605 C.

After complete deslagging the crucible was moved back to its blowingposition and the blowing device inserted into the crucible. The nozzleorifice was adjusted to a distance of 400 mm. from the bath, the oxygenpressure adjusted to 8 kg./sq. cm. superatmospheric pressure and theblowing of the bath continued for 4.5 minutes. At the same time, 70 kg.powdered coke and kg. lime dust were introduced under no pressurethrough the downcomer into the interior of the jet and thereby into theinterior of the reaction zone. During the last portion of this heatingperiod, about Z2 minute before the end of the blowing, 87 kg.ferro-chromium having a composition of 1.39% C, 0.80% Si, 0.040% P,0.076% S, 66.10% Cr were added through a chute. Then the oxygen supplywas interrupted, the blowing device moved out of the crucible andsamples taken. The composition of the steel was: 0.05% C, 0% Si, 0.28%Mn, 0.018% P, 0.027% S, 0.97% Cr. The temperature was 1640 C. Aftertapping the recovery was 86.2%.

Example 10.Increase of a charge by reduction of are A charge was formedfrom 4800 kg. liquid crude iron having a composition of 4.05% C, 0.97%Si, 1.53% Mn, 1.68% P and 0.030% S. After 50 kg. scale, 30 kg. bauxiteand 150 kg. lime in lumps had been added the charge was blown with theblowing device as in the previous examples but with the downcomer closed(pressure 14 kg./sq. cm., nozzle distance 400 mrn.). After a blowingperiod of 6.5 minutes the oxygen supply was interrupted, the blowingtube removed and a sample taken. The composition of the steel was asfollows: 2.10%. C, 0% Si, 0.58% Mn, 0.104% P, 0.028% S. The temperaturewas 1560 C.

The crucible was moved back into blowing position and the blowing devicemoved into the crucible. The nozzle orifice was adjusted to a distanceof 600 mm. from the bath, the oxygen pressure adjusted to 14 kg./ sq.cm. superatmospheric pressure and the blowing of the bath continued for28.5 minutes. During this blowing period, 1,500 kg. fine ore, 1,000 kg.powdered coke and 210 kg. lime dust were simultaneously added under nopressure through the downcomer into the interior of the jet and therebyinto the interior of the reaction zone. The ore had the followingcomposition: 71% Fe, 0.1% Mn, 1.7% 306 0.05% CaO, 0.01% S, 0.08% P, 4.5%A1 0 0.1%

After this blowing period carried out under a reducing atmosphere theoxygen supply was shut down, the nozzle removed and a sample taken. Thecomposition of the steel was as follows: 2.27% C, 0% Si, 0.25% Mn,0.078% P, 0.035% S. The temperature was 1280 C.

After partial deslagging the crucible was moved back to its blowingposition, 400 kg. lime in lumps were added through a chute, the blowingdevice moved into the crucible and while the downcomer was closed theblowing was continued for 13 minutes under a pressure of 14 kg./sq. cm.superatmospheric pressure and with a nozzle distance of 400 mm. Then theblowing was terminated, a sample taken and the temperature measured. Thecomposition was: 0.03% C, 0% Si, 0.26% Mn, 0.017% P 0.026% S. Thetemperature was 1660 C.

After deslagging the steel was tapped and teemed. The recovery was85.2%.

Example ]1.Conversion of high-phosphorus crude iron into steel A chargewas formed from 6450 kg. liquid crude iron having a composition of 3.80%C, 0.83% Si, 0.45% Mn, 0.950% P, 0.040% S. After an addition of 150 kg.scarfing scale and 50 kg. bauxite the charge was blown by a blowingdevice as in the previous examples so that a reaction zone was formed.The distance of the blowing device from the bath was 400 mm., the oxygenpressure was 10 kg./sq. cm. superatmospheric pressure. During the firstblowing period of 9 minutes, 400 kg. lime dust were added under nopressure through the downcomer and sucked from the mouth of thedowncomer into the interior of the jet and moved into the interior ofthe reaction zone. After a first blowing period of 9 minutes the oxygensupply was interrupted, the blowing device withdrawn and 50 kg. ore inlumps added to the bath in one batch through a chute. A violent reactionensued for 1 to 2 minutes. The crucible was tilted and samples taken.The composition of the steel in this stage was: 2.10% C, 0.06% Si, 0.18%Mn, 0.092% P, 0.037% S. The composition of the slag was: 18.00% FeO,2.30% MnO, 10.75% SiO ,40.88% CaO, 4.43% MgO 12.78% P 0 7.31% A1 0 Thetemperature was 1520" C.

After deslagging the crucible was moved back to its blowing position,kg. scale, 50 kg. bauxite and 400 kg. lime in lumps introduced andblowing continued under a pressure of 8 kg./sq. cm. superatmosphericpressure and r a nozzle distance of 400 mm. while the downcomer wasExample 12.-Cnversi0n of basic bessemer iron into steel To a charge of6580 kg. liquid crude iron having a composition of 3.62% C, 0.27% Si,1.05% Mn, 1.750% P, 0.053% S there was added 150 kg. scarfing scale and50 kg. bauxite. The charge was blown by means of a blowing device as inthe previous examples to form a reaction zone. The distance of theblowing device from the bath was 400 mm. and the oxygen pressure was 10kg../sq. cm. superatmospheric pressure. During the first blowing periodof 10.5 minutes, 450 kg. lime dust were supplied under no pressurethrough the downcomer and sucked up from the mouth of the downcomer intothe interior of the jet and brought into the interior of the reactionzone. After the first blowing period of 10.5 minutes the oxygen supplywas interrupted, the blowing device removed and 50 kg. ore in lumpsadded to the bath in one batch through a chute. A violent reactionensued for 2 to 2.5 minutes. The crucible was tilted and samples taken.The compoSitiOn of the steel at this stage was: 1.98% C, 0% Si, 0.25%Mn, 0.225% P, 0.046% S. The composition of the slag was: 16.30% FeO,6.28% MnO, 3.64% SiO 42.30% CaO, 1.64% MgO, 21.90% P 0 5.23% A1 0 Thetemperature was 1540 C.

After deslagging, the crucible was moved back to its blowing position.100 kg. scale, 50 kg. bauxite and 400 kg. lime in lumps were introducedby means of a chute and the blowing continued under a pressure of 14kg./ sq. cm. superatmospheric pressure and with .a nozzle distance of400 mm. while the downcomer was closed. The duration of this secondblowing period was 6.5 minutes.

Then the blowing device was moved out of the crucible, the crucibletilted and a steel sample taken. The composition was: 0.03% C, 0% Si,0.10% Mn, 0.014% P, 0.020% S. The temperature is 1655 C. Afterdeslagging, the steel was tapped and teemed. The recovery was 85.7%.

What is claimed is:

1. A method of carrying out metallurgical processes comprising blowingan oxygen-containing gas against the surface of a charge comprisingmolten crude iron in a vessel having a refractory lining, said gas beingblown through an annular orifice to form an annular jet impinging onsaid surface in an annular zone, said jet bounding and defining apassage within said jet, and discharging solid particles by gravitythrough said passage against the surface of said charge inwardly of saidannular zone during at least part of the time said gas is being blownagainst said surface of said charge.

2. A method according to claim 1 wherein said gas is selected from thegroup consisting of oxygen and oxygenenriched gases.

3. A method according to claim 1 wherein said solid particles areslag-forming substances.

4. A method according to claim 1 wherein said solid particles are heatgenerating substances.

5. A method according to claim 1 wherein said solid particles are ironoxides and alloying substances.

6. A method according to claim 1 wherein said solid particles arealloying substances.

7. The method set forth in claim 1 wherein said solid particles comprisecarbonaceous material and the amounts of oxygen-enriched gas andcarbonaceous material supplied to said charge are in such relation thatan oxidizing atmosphere is produced.

8. The method set forth in claim 1 wherein said solid particles comprisecarbonaceous material and the amounts of oxygen and carbonaceousmaterial supplied to said charge are in such relation that a neutralatmosphere is produced.

9. The method set forth in claim 1 wherein said solid particles comprisecarbonaceous material and the amounts of oxygen and carbonaceousmaterial supplied to said charge are in such relation that a reducingatmosphere is produced.

10. The method set forth in claim 1 in which the solid particles areiron oxide and carbonaceous material.

References Cited by the Examiner UNITED STATES PATENTS 2,446,511 8/48Kerry et al. -43 2,515,670 7/50 Slottman et al. 75-43 2,593,505 4/52Wagstaff 75-60 2,598,393 5/52 Kalling et al. 75-60 2,817,584 12/57 Kootzet al. 75-60 2,836,411 5/58 Auer 266-34 2,862,811 12/58 Eketorp et al.75-60 2,937,864 5/60 Kesterton 266-34 2,950,186 8/60 Allard et al. 75-603,988,443 6/61 Metz 75-52 2,990,271 6/61 Dierker 75-41 3,001,864 9/61Muller et al. 75-129 FOREIGN PATENTS 1,226,680 2/59 France.

845,643 8/52 Germany.

898,309 11/59 Germany.

OTHER REFERENCES Jour. of Metals, June 1956, p. 762.

BENJAMIN HENKIN, Primary Examiner.

RAY K. WINDHAM, MARCUS U. LYONS, Examiners.

1. A METHOD OF CARRYING OUT METALLURIGCAL PROCESSES COMPRISING BLOWINGAN OXYGEN-CONTAINING GAS AGAINST THE SURFACE OF A CHARGE COMPRISINGMOLTEN CRUDE IRON IN A VESSEL HAVING A REFRACTORY LINING, SAID GAS BEINGBLOWN THROUGH AN ANNULAR ORIFICE TO FORM AN ANNULAR JET IMPINGING ONSAID SURFACE IN AN ANNULAR ZONE, SAID JET BOUNDING AND DEFINING APASSAGE WITHIN SAID JET, AND DISCHARGING SOLID PARTICLES BY GRAVITYTHROUGH SAID PASSAGE AGAINST THE SURFACE OF SAID CHARGE INWARDLY OF SAIDANNULAR ZONE DURING AT LEAST PART OF THE TIME SAID GAS IS BEING BLOWNAGAINST SAID SURFACE OF SAID CHARGE.